Method of synthesizing a high energy yielding solid material



June 24, 1969 E. J. HELLUND 3,451,910

METHOD OF SYNTHESIZING A HIGH ENERGY YIELDING SQLID MATERIAL Filed Sept.29, 1964 Sheet of 2 EMIL J. HELLUND INVENTOR.

June 24, 1969 E. J. HELLUND 3,451,910

METHOD OF SYNTHESIZING A HIGH ENERGY YIELDING SOLID MATERIAL Filed Sept.29, 1964 Sheet 2 0192 Fig 3 EMIL J. HELLUND INVENTOR.

United States Patent US. Cl. 204-168 8 Claims This invention relatesgenerally to the stabilizing of energetic molecular and atomic states,and more particuparly concerns processes [for effecting stabilization ofthese high energy molecular states in solid matter (hybridization), aswell as the products (hybrids) formed by practicing such processes.

Generally speaking, the invention concerns creation of solid hybridmaterial wherein sufficient atoms are in metastable states characterizedby greater than normal separation of charge conjugate (positive andnegative) pairs, that the material as a whole will exhibit an energyyield significantly above that of the normal combustion energy yield ofthe material. In this regard, one may view such material as a hybridcontaining matter in ion-electron complexes or metastable states(characterized by a large separation of charge conjugate pairs),combined with matter in the ground state (characterized by a relativelymuch closer, or normal, association of charge conjugate pairs). Thehybrid material might be otherwise characterized as a plasmasol,denoting an alloy of a plasma in a solid matrix. Further, the electricalcharge is not free to move through the matrix. Mobility of charge isassociated with decay of the activated or metastable state. Practicalhandling of the hybrid material, prior to transformation of potentialenergy during ultimate usage, requires low decay rates.

Basically, the method for creating the hybrid material includes thesteps of raising the energy level of a gas by converting the gas to aplasma, and condensing in a combined form (hybrid) the gas in raisedenergy state and a solid carrier or matrix, the latter typically beingcombustible. More specifically, the method involves the steps of forminga gaseous system having a first component characterized as electricallyinsulative and a second component characterized as in a raised energy orplasma state, and then condensing these components in the form of asolid hybrid material with at least some of this second component inraised energy or metastable state therein.

Typically, the condensing step involves removal of heat from the solidhybrid material during formation thereof for the following reasons.Whatever the structure of the solid hybrid material, it is capable ofbeing destroyed by addition of energy to the various chemical bonds. Ifsuch energy is present in the reagent system during formation of thebonds, as during condensation of the reagents, it must be rapidlywithdrawn. Accordingly, it will be seen that success in producing theresultant hybrid solid material involves a solution to the problem ofmaintaining sufiicient energy input to create the excited states or highenergy levels, yet removing suflicient energy to obviate destructivedecay of the condensed hybrid. This problem is solved by rapidlyWithdrawing excesss energy from the reagents as they condense and formbonds characteristic of the resultant new hybrid matter, excess energywithdrawal being accomplished by a rapid heat quenching action.

3,451,910 Patented June 24, 1969 One class of systems found to becompatible with the above energy requirements consists of helium, aswell as oxygen and nitrogen as the plasma convertible gas or secondcomponent, with the first component consisting of organics exhibitinghigh resistivity to electron movement and low mobility for the atomicconstituents. Otherwise stated, the usable organics consist of thosehaving very low electrical conductivity and also poor thermalconductivity, together with a high degree of cohesiveness in the hybridstate.

Relating the synthesis process to the above class of systems, capable ofresulting in the production of a high energy yielding solid material, itincludes the steps of vaporizing an electrically insulative organic,mixing the vapor with a plasma in a reaction zone, subjecting that zoneto an electrical field at lowv pressure to produce a glow discharge forsustaining the plasma, presenting a surface to said zone for receivingdeposition of material therefrom, and removing heat from that surfaceand from material deposited thereon. Oxygen and nitrogen are typicallyadmitted to and confined in gaseous state in the reaction zone at lowpressure to form the plasma, and helium is also confined in the reactionzone. The organic vapor typically consists of a hydrocarbon such asparaffin and specifically ceresin. The explosive known as RDX(cyclo-trimethylene-trinitramine) is also recommended as a sourcematerial for the resultant hybrid product. In addition, moisture isinitially substantially excluded from the reaction zone, and thepressure therein is kept within a narrow preferred range and belowmicrons of mercury. Optimum operating parameters may be determined byexperiment, once the researcher is familiar with the principles setforth herein.

It is a further object of the invention to provide novel hybridcompositions of matter characterized as containing matter in high energystate and as yielding high energy upon combustion and at extremely rapidrates. These hybrids also display characteristically new infraredabsorption patterns, and may be defined in terms of such absorption, orotherwise as the products obtained by the processes described above andto be described, in view of the considerable difliculty in exactlychemically defining them.

These and other objects and advantages of the invention will appear ingreater detail from the following detailed description, and the drawingsin which:

FIGURE 1 is an energy level diagram;

FIGURE 2 is a schematic vertical section taken through reactor apparatususable in practicing the inventive process;

FIGURE 3 is a frontal view of a grid in FIGURE 2 and partly broken awayto show plate structure behind the grid; and

FIGURE 4 is a perspective showing, in relief, ocf a typical yieldfunction.

A discussion of molecular energy should precede a discussion of thesynthesis method, product and apparatus. In general, there are twodifferent approaches to storing energy in matter. One approach bringsnuclear forces into consideration, whereas the other concerns electricalforces existing between electrons and protons residing in the variousnuclei of the molecules. The present invention is concerned with thesecondor latter approach, and involves what may be termed a high energystate.

To understand what is meant in a structural sense by a high energy statein atomic and molecular systems, it

should be recalled that the absolute value of the energy of a givenstate, all forces being electrostatic, is equal to the average value ofthe kinetic energy of the electrons, or, one-half the absolute value ofthe average potential energy of the electrons in the field of thepositive charges residing in the nuclei of the atom. If the energy of agiven state is increased, the result can be interpreted, according toFIGURE 1, as a decrease of binding energy, i.e. the energy binding theelectrons to the protons. In FIGURE 1, the numeral B denotes the energynecessary to dissociate the molecule, that is, to decrease the bindingenergy to zero. If energy A is added to the system, the molecule isdepicted as reaching a level at which the remaining energy necesary fordissociation is B The actual energies of the two states are, accordingto the zero energy level shown, equal to B and B respectively, with Bless than B1.

In the activated state, therefore, the system will have an averagekinetic energy equal to B and a potential energy equal to -2B Since thepotential energy between the positive charge on the representativenucleus, Ze, and the negative charge on the electron, e, is equal to thefollowing expression:

Ze r (1) where r is the distance between the electron and the nucleus,it can be stated that:

I. B 2 B1 (activated state) (ground state) that is, an increase incharge separation must accompany an increase in energy of a given atomicor molecular system, neglecting the effect of repulsion between likecharges.

An increase in charge separation will in general occur by expansion ofthe entire structure under consideration; however, a change of stateofenergy of a given solid need not imply a uniform expansion of all bonds,but can take place in such a way as to absorb energy in only a limitednumber of charge conjugate pairs. Such states can be viewed ascontaining activated material embedded in a lower energy matrix.

The picture of the activated state just presented serves to emphasizethe rather special chemical and physical properties associated with it.One should consider the resultant material, owing to its changed bondingarrangement, as a new compound difiering in an essential way from theground state material. Viewed in terms of an increase of positive andnegative charge separation, one can regard the high energy solid stateas a hybrid of an ion-electron state combined with a ground statecharacterized by a much closer association of charge conjugate pairs.For this reason the state will frequently be referred to as a hybrid ora plasmasol to denote an alloy of a plasma in a solid matrix. As such,one should not allow this viewpoint to suggest that the charges are freeto move through the matrix. Mobility is the vehicle by which the excitedstate decays, that is, a movement of charge is necessary for atransformation of potential energy and therefore of the total energy ofthe state. The charges must be restricted in movement by the existenceof barriers, and if these are sutficiently high, the decay rate of thestate will be low enough to permit practical utilization of thematerial.

With this background one can proceed to a discussion of just how such ahybrid or plasmasol is to be synethesized. Whatever the structure of thehybrid compound, it is capable of being destroyed by adding energy tothe various bonds. The mechanism of synthesis must therefore provide forrapid removal of such energy if present at formation of the bonds, or,must avoid the introduction of such energy during the synthesis. Iflarge amounts of energy are available during compounding it is difficultto avoid destructive triggering of decay mechanisms (induced decay).Insufiicient energy for the creation of the excited states (high energylevels) would preclude their formation as a violation of the law ofconservation of energy. Accordingly, the reactive mechanism to beemployed must supply the correct molecules with just the right amount ofenergy and provide also a fast quenching environment for removal ofexcess energy.

Referring now to the specific apparatus seen in FIGURE 2, a vacuumchamber 10 is provided with insulative walls which typically include 3inch thick micarta panels 11 as Well as 2 inch thick Plexiglas windows12 and 13, suitable gaskets being used at the joints. An insulativeplate 14 covers an openings 15 through window 12, and supports heliuminlet duct 16, gas inlet duct 17, and a thermocouple probe 18 useful forsensing the chamber interior pressure. Helium source 19 is connected toduct 16 via appropriate valving 20, and nitrogen and oxygen sources 22and 23 are connected to ducting 17 via valves 25 and 26 Chamber 10 istypically 600 millimeters long between the outer surfaces of windows 12and 13.

Located within the chamber interior are two evaporators in the form ofstainless steel receptacles 27 and 28 for holding the insulative organicmaterial to be evaporated and shown at 29. The receptacles may beheated, as for example by heater elements 30 electrically connected at31 to a current source 32 having a control 33 enabling manual control ofheating and hence the rate of evaporation of the organic material 29 andthe rate of deposition of the hybrid. The receptacles are spaced about114 millimeters below the undersurface 34, and have vapor outlets 35facing toward one another and toward grids 36 and 37, arrows 38depicting the flow of vapor toward the latter.

Grids or electrodes 36 and 37 are spaced about 83 millimeters from thecenters of receptacles 27 and 28, respectively, and consist of finestainless steel Wire in mesh form and having openings of at least A inchby 4 inch size. The spacing between the grids is about 4 inches. Asource of high voltage for the grids is indicated at 138, and ascontrollable at 238 the applied AC-voltage being sufiicient to providean ionizing glow discharge within the reaction Zones 39 and 40 tosustain the gaseous plasma therein. Central brass plate 41 acts as agrounded electrode for the glow discharge, the latter being shuntedaround the edges or peripheries of a pair of thin nonconductive plates42 and 43 acting as receivers for the deposited material. Plates 42 and43 are in direct contact with opposite faces of the brass plate 41.

Each of the glass plates 42 and 43, the grids 36 and 37 and the groundedbrass plate 41 is about 178 millimeters square; the glass plates 42 and43 being approximately 2 millimeters thick and carried by the groundedplate 41. The spacing between glass plates 42 and 43 and the respectiveelectrodes 36 and 37 is 38 millimeters, and the thickness of groundedplate 41 is approximately 13 millimeters. With source 38 operating at2,000 volts and 60 cycles per second, a current of 20 milliamperes ismaintained in the reaction zones 39 and 40 when the pressure is reducedin the chamber as described below.

Central plate 41 contains a passage 44, better seen in FIGURE 3, throughwhich liquid nitrogen is circulated at 196" C. inlet and outlet ducts 45and 46 communicating between the opposite ends of passage 44 and theliquid nitrogen source indicated at 47. A vacuum pump is shown at 48 ashaving its inlet in communication with the interior 49 of the chamber 10via ducting 50 having a cold trap 51 in series therewith. The pump istypically capable of reducing the chamber interior pressure to 1 micronof mercury (1 Hg).

The following example is typical of the processing: samples of ceresin(a mixture of long chain aliphatic hydrocarbons with carbon numbersbetween 20 and 35, the average carbon number is approximately 28), areplaced in the evaporator and the chamber 10 is closed, Oxygen andnitrogen gas are admitted to the chamber in the proportion 1 mole of Oto 4 moles of N as exists in air.

The chamber is then pumped down to a partial pressure of oxygen andnitrogen of about 40 microns of mercury. Liquid nitrogen (at -l96 C.) isthen circulated through plate 41, and the oxygen and nitrogen pressurein chamber drops to between 28 and 32 (optimum is 30) microns ofmercury. Glass plates 42 and 43 are, accordingly, kept cooled to near196 C. The Vaporizers are then started to vaporize ceresin, and heliumis admitted to the chamber, so that the helium and ceresin vapor make upbetween 17 and 23 microns of mercury (optimum is 20 Hg), and so that thetot-a1 pressure in the chamber is raised to between 45-55 microns ofmercury, and preferably near 50 microns of mercury. A glow discharge isthen produced in the reaction zones 39 and 40 by connecting 60-cycle2,000-volt source 38 thereto, producing a current of about 20 milliampsthrough the plasma in those zones. The evaporation of ceresin is thencontrolled to deposit between 20 and 90 milligrams per hour on thenon-conducting plates. During such deposition, oxygen and nitrogen aremaintained in the chamber in the correct proportions and the vacuum pumpoperated to maintain the pressure within the range 45-55 microns ofmercury. Arrows 80 indicate the molecular condensation current path inthe reaction zones. After 4 /2 hours the equipment is shut down and thesample deposits are recovered in the form of thin, very hard filmshaving cellophanelikeappearance and being light brown in color. In thisway about 288 milligrams of sample hybrid material in polymerized formmay be produced over a 4 /2 hour run, the material typically yieldingbetween 17,000 and 45,000 calories per gram upon combustion. The sameweight of normal ceresin will typically yield only about 10,000 caloriesper gram upon combustion. Some improvement in yield can be realized byoperating the reactor so as to vary, i.e. increase and decrease the rateof deposition of the hybrid during a run, This can be effected throughcontrol of ceresin vaporization. It is also contemplated that the rawmaterial need not be in solid state, initially, so that vapor or gaseousstate organic materials of insulative quality may be directly introducedinto the reactor chamber.

Removal of the films from the cold surfaces. of the non-conductingplates may be accomplished by scraping or by utilization of an undercoatof inert material which will spall otf the cold plate upon an increasein temperature thereof. The spallative coat must be free of breakdown inan electrical discharge environment, should be non-reactive and shouldhave a low vapor pressure to prevent interference with the collisiondynamics in the glow discharge. Xenon and radon satisfy these requirements and may be sprayed on the exposed surfaces of the non-conductingplates 42 and 43 prior to process coating by the hybrid material. Forthis purpose, brass jets 52 and 53 are provided as shown in FIGURE 2 tohave outlets in chamber interior 49 and directed toward the cold plates,the jets communicating via line 54 with source 55 via valving 56. Someimprovement in uniformity of xenon coating of plates 42 and 43 may berealized by preliminary introduction of a gaseous fluoride such astetrafluoromethane into the chamber 49 at a pressure of about 150microns of mercury, and running the glow discharge in reaction zones 39and 40 for about 10 minutes.

The presence in the reaction zones of oxygen and nitrogen is necessaryto the creation of the high energy state in the hybrid material. Theprecise nature of the function of these components is not yet known andmust await more elaborate study, since a host of compounds and radicalscan be created involving 0 and N This follows from the occurrence offragmentation or cracking of the organic material such as ceresin in thereaction zones. Among those believed to be present in the reaction zonesare H 0, NH NO, N0 C0, C0 CN and HCN.

The following additional examples further illustrate the operation ofthe equipment of FIGURE 2 to produce the high yield product:

ADDITIONAL EXAMPLE 1 Time Operation 0830 The chamber interior pressurewas pumped down to 45 microns of mercury.

0845 Liquid nitrogen was circulated through center electrode plate 41 tocool it to operating temperature.

0900 The substrate plates 42 and 43 were cold; Vaporizers 27 and 28 wereelectrically heated by current of 43 amperes and 0.52 volt, or 22.3watts each. A magenta colored glow discharge in zones 39 and 40 wasproduced by energizing grids 36 and 37 at 2000 volts and at 23milliamperes current, or 40 watts.

0900 to 1330. Pressure in chamber interior 49 was kept close to 50microns of mercury, and gases included oxygen and nitrogen in proportion1 mole of oxygen to 4 moles of nitrogen, as wleltl as helium. The sampleslowly deposited on the p a es.

1330 The run was ended after 4% hours, and the equipment was shut downto allow the cold plates and deposited sample to warm up.

1410 The sample was recovered by placement of the substrate plates in anitrogen gas atmosphere in a dry box, following which the deposits werescraped 003 the plates and recovered as three samples. Burning 01' thesamples in a bomb calorimeter indicated the following yields:

Weight (mg) ADDITIONAL EXAMPLE 2 Time Operation 0830 Pumped down chamberinterior and at 0840 commenced cooling down the plate 41 by liquidnitrogen circulation until air pressure in chamber reduced to 30 micronsof mercury.

0910 The substrates were now cold and pressure in the chamber was at 20microns of mercury. Helium was admitted to the chamber interior untilpressure rose to 50 microns of mercury. The run was started with theVaporizers operated at 43 amperes and 0.52 volt (22.3 watts) and theglow discharge at 2800 volts and 14.3 milliamperes (40 watts). The glowdischarge was magenta in color, excepting that proximate the substratesurfaces the discharge was slightly greenish.

1000 Discharge voltage supplied to electrodes 36 and 37 increased to2800 volts at 20 milliamperes (56 watts).

was

1100 Discharge voltage dropped to 2100 volts at 20 milliamperes 412vlrlatts), and color of discharge was observed to be u1s 1340 Ended runafter 4% hours, and began warm-up with helium being admitted to ringcell interior to 25 mm. pressure during the Warm-up. Sample observed tohave same appearance as in Additional Example 1 above.

1420 Recovered sample using same procedure as in Example 1 above; samplewas divided into 4 parts and these had the following yields upon testingin a combustion calorimeter:

Sample No. Weight (mg) Yield (caL/gram) ANALYSIS OF THE HYBRID While itis extremely difiicult to determine what complex phenomena occur in theplasma during reaction in zones 39 and 40, it is possible to reachvaluable conclusions by studying the effect of the presence of Water ormoisture in chamber interior 49 upon the combustion energy of the hybridproduct. In this regard, water vapor was leaked into the system as aconstituent of air, and by measuring the absolute humidity and thepressure of air maintained inside the reactor chamber under set vacuumpumping conditions, and by recording the combustion energy of the hybridit has been possible to determine the relationship between the two.

An experimentally drrived expression for the yield in kilocalories pergram of hybrid material obtained through operation of the FIGURE 2apparatus is as follows:

P.H I' f so L 192 P rai gy]? where EQUATION 3 is valid only for a2000-volt 20-milliamperes glow discharge in the reaction zones 39 and40.

FIGURE 4 is a relief map of the yield function Y showing its criticaldependence on absolute humidity H and initial warm pressure p, theheight of the hump at different points indicating yield values. Thisparticular relief map is indicative of a class of such maps, theparticular values on the map shown being valid only for the system ofgases described in the detailed examples above, and for a runningpressure in the reactor of 50 Hg, total. It is clear from this reliefmap that moisture should be excluded from the reaction zones in thereactor in order to reach maximum energy yields in the hybrid materialand to avoid chemisorption. It is also clear from this relief map thatthe initial warm pressure in the reaction zones must be kept within acritical range to realize the high energy yields. Points on the map showactual energy yield values for hybrid materials produced by the processdescribed herein.

Referring again to the plasmasol synthesis process, the resultant samplematerial in film form is found to consist of a dielectric exhibitinghigh resistivity. Also, while the frequency of the glow dischargevoltage does not presently appear critical, the voltage itself should bemaintained in the neighborhood of 2,000 volts and within the range 1,500to 3,000 volts, and it is believed that the discharge current should bebetween 30 milliamperes, these values being for the particular sizeapparatus described above. As to the usable organic source materials, itis presently believed that these include the heavier (35 carbon atoms)organics, as for example branched or straight chain parafiin, havingoxidizing elements or groups hooked onto the carbon atoms.

I claim:

1. The method of synthesizing a high energy yielding solid material,that includes forming a vapor consisting of long chain hydrocarbonmolecules with carbon numbers between about 20 and 35, mixing said vaporwith a plasma in a reaction zone, confining oxygen and nitrogen ingaseous state at low pressure in said zone to form said plasma,subjecting said zone to an electrical field at low pressure to produce aglow discharge for sustaining the plasma, presenting a surface to saidzone for receiving deposition of material therefrom and in solid form,and removing heat from said surface and from material depositedthere-on.

2. The method of claim 11 including the step of confining helium at lowpressure in said zone.

3. The method of claim 1 in which moisture is initially substantiallyexcluded from said zone and said low pressure is maintained within therange 45 to microns of mercury.

4. The method of claim 3 in which oxygen and nitrogen are present insaid zone in approximately the proportion 1 mole of oxygen to 4 moles ofnitrogen.

5. The method of claim 3 in which said heat removal is carried out tomaintain said surface at a temperature --l C. (:50 C.).

6. The method of claim 1 including the step of controlling the rate ofvapor formation in order to control the rate of deposition of said solidform material.

7. The method of claim 1 including the step of varying the rate ofdeposition of said material.

8. The product obtained from the process of claim 1.

References Cited FOREIGN PATENTS 4/ 1939 Great Britain.

REUBEN EPSTEIN, Primary Examiner.

U.S. C1.X.R.

1. THE METHOD OF SYNTHESIZING A HIGH ENERGY YIELDING SOLID MATERIAL,THAT INCLUDES FORMING A VAPOR CONSISTING OF LONG CHAIN HYDROCARBONMOLECULES WITH CARBON NUMBERS BETWEEN ABOUT 20 AND 35, MIXING SAID VAPORWITH A PLASMA IN A REACTION ZONE, CONFINING OXYGEN AND NITROGEN INGASEOUS STATE AT LOW PRESSURE IN SAID ZONE TO FORM SAID PLASMA,SUBJECTING SAID ZONE TO AN ELECTRICAL FIELD AT LOW PRESSURE TO PRODUCE AGLOW DISCHARGE FOR SUSTAINING THE PLASMA, PRESENTING A SURFACE TO SAIDZONE FOR RECEIVING DEPOSITION OF MATERIAL THEREFROM AND IN SOLID FORM,AND REMOVING HEAT FROM SAID SURFACE AND FROM MATERIAL DEPOSITEDTHERE-ON.